Field
Exemplary Embodiments of the present disclosure relate to a method of processing a workpiece, and particularly, to a method including etching of a tungsten-containing film.
Related Background Art
When manufacturing an electronic device such as a semiconductor device, etching is performed with respect to an etching target layer by plasma processing to form an opening in the etching target layer. In the etching, it is required to form an opening having a high aspect ratio. That is, it is required to form an opening that is narrow and deep.
In order to form an opening having a high aspect ratio, it is necessary to reduce consumption of a mask on the etching target layer during the etching of the etching target layer. To this end, etching is performed with respect to a tungsten film to form a mask. Typically, the tungsten film is etched with a plasma of a processing gas including chlorine gas. The etching of the tungsten film is disclosed in, for example, Japanese Patent Application Laid-Open Publication No. 2014-203912.
When a film containing tungsten (hereinafter, referred to as “tungsten-containing film”) is etched with the plasma of the processing gas including chlorine gas, tungsten chloride is formed through a reaction between tungsten and chlorine. Tungsten chloride has low volatility, and adheres to a workpiece. As a result, an opening, which is formed in the tungsten-containing film, has a tapered shape. That is, an opening, in which a width at a deep position is smaller than a width at a shallow position, is formed. Accordingly, there is a demand for a technology of forming an opening having high verticality in the tungsten-containing film.